package net.minecraft.client.texture;

import net.fabricmc.api.EnvType;
import net.fabricmc.api.Environment;
import net.minecraft.util.Util;
import net.minecraft.util.math.ColorHelper;

@Environment(EnvType.CLIENT)
public class MipmapHelper {
	private static final int MIN_ALPHA = 96;
	private static final float[] COLOR_FRACTIONS = Util.make(new float[256], list -> {
		for (int i = 0; i < list.length; i++) {
			list[i] = (float)Math.pow(i / 255.0F, 2.2);
		}
	});

	private MipmapHelper() {
	}

	public static NativeImage[] getMipmapLevelsImages(NativeImage[] originals, int mipmap) {
		if (mipmap + 1 <= originals.length) {
			return originals;
		} else {
			NativeImage[] nativeImages = new NativeImage[mipmap + 1];
			nativeImages[0] = originals[0];
			boolean bl = hasAlpha(nativeImages[0]);

			for (int i = 1; i <= mipmap; i++) {
				if (i < originals.length) {
					nativeImages[i] = originals[i];
				} else {
					NativeImage nativeImage = nativeImages[i - 1];
					NativeImage nativeImage2 = new NativeImage(nativeImage.getWidth() >> 1, nativeImage.getHeight() >> 1, false);
					int j = nativeImage2.getWidth();
					int k = nativeImage2.getHeight();

					for (int l = 0; l < j; l++) {
						for (int m = 0; m < k; m++) {
							nativeImage2.setColorArgb(
								l,
								m,
								blend(
									nativeImage.getColorArgb(l * 2 + 0, m * 2 + 0),
									nativeImage.getColorArgb(l * 2 + 1, m * 2 + 0),
									nativeImage.getColorArgb(l * 2 + 0, m * 2 + 1),
									nativeImage.getColorArgb(l * 2 + 1, m * 2 + 1),
									bl
								)
							);
						}
					}

					nativeImages[i] = nativeImage2;
				}
			}

			return nativeImages;
		}
	}

	private static boolean hasAlpha(NativeImage image) {
		for (int i = 0; i < image.getWidth(); i++) {
			for (int j = 0; j < image.getHeight(); j++) {
				if (ColorHelper.getAlpha(image.getColorArgb(i, j)) == 0) {
					return true;
				}
			}
		}

		return false;
	}

	private static int blend(int one, int two, int three, int four, boolean checkAlpha) {
		if (checkAlpha) {
			float f = 0.0F;
			float g = 0.0F;
			float h = 0.0F;
			float i = 0.0F;
			if (one >> 24 != 0) {
				f += getColorFraction(one >> 24);
				g += getColorFraction(one >> 16);
				h += getColorFraction(one >> 8);
				i += getColorFraction(one >> 0);
			}

			if (two >> 24 != 0) {
				f += getColorFraction(two >> 24);
				g += getColorFraction(two >> 16);
				h += getColorFraction(two >> 8);
				i += getColorFraction(two >> 0);
			}

			if (three >> 24 != 0) {
				f += getColorFraction(three >> 24);
				g += getColorFraction(three >> 16);
				h += getColorFraction(three >> 8);
				i += getColorFraction(three >> 0);
			}

			if (four >> 24 != 0) {
				f += getColorFraction(four >> 24);
				g += getColorFraction(four >> 16);
				h += getColorFraction(four >> 8);
				i += getColorFraction(four >> 0);
			}

			f /= 4.0F;
			g /= 4.0F;
			h /= 4.0F;
			i /= 4.0F;
			int j = (int)(Math.pow(f, 0.45454545454545453) * 255.0);
			int k = (int)(Math.pow(g, 0.45454545454545453) * 255.0);
			int l = (int)(Math.pow(h, 0.45454545454545453) * 255.0);
			int m = (int)(Math.pow(i, 0.45454545454545453) * 255.0);
			if (j < 96) {
				j = 0;
			}

			return ColorHelper.getArgb(j, k, l, m);
		} else {
			int n = getColorComponent(one, two, three, four, 24);
			int o = getColorComponent(one, two, three, four, 16);
			int p = getColorComponent(one, two, three, four, 8);
			int q = getColorComponent(one, two, three, four, 0);
			return ColorHelper.getArgb(n, o, p, q);
		}
	}

	private static int getColorComponent(int one, int two, int three, int four, int bits) {
		float f = getColorFraction(one >> bits);
		float g = getColorFraction(two >> bits);
		float h = getColorFraction(three >> bits);
		float i = getColorFraction(four >> bits);
		float j = (float)((float)Math.pow((f + g + h + i) * 0.25, 0.45454545454545453));
		return (int)(j * 255.0);
	}

	private static float getColorFraction(int value) {
		return COLOR_FRACTIONS[value & 0xFF];
	}
}
